Assessment of DNA extraction methods for human gut mycobiome analysis.

The gut mycobiome plays an important role in the health and disease of the human gut, but its exact function is still under investigation. While there is a wealth of information available on the bacterial community of the human gut microbiome, research on the fungal community is still relatively limited. In particular, technical methodologies for mycobiome analysis, especially the DNA extraction method for human faecal samples, varied in different studies. In the current study, two commercial kits commonly used in DNA extraction, the QIAamp® Fast DNA Stool Mini Kit and DNeasy PowerSoil Pro Kit, and one manual method, the International Human Microbiome Standards Protocol Q, were compared. Furthermore, the effectiveness of two different bead-beating machines, the Mini-Beadbeater-16 and FastPrep-24TM 5G, was compared in parallel. A mock fungal community with a known composition of fungal strains was also generated and included to compare different DNA extraction methods. Our results suggested that the method using the DNeasy PowerSoil Pro Kit and Mini-Beadbeater-16 provides the best results to extract DNA from human faecal samples. Based on our data, we propose a standard operating procedure for DNA extraction from human faecal samples for mycobiome analysis.

Ulcerative Colitis Diagnosed through Evaluation of Underlying Diseases in a Pyoderma Gangrenosum Adolescent without Gastrointestinal Symptoms.

Pyoderma gangrenosum (PG) is a rare, non-infectious, neutrophilic dermatosis characterized by painful ulcers with indistinct borders and peripheral erythema. The diagnosis of PG requires the exclusion of other causes of similar appearing skin manifestations, including vasculitis and infections. The pathogenesis of PG is not clear; however, dysregulation of the immune system has been suggested in previous studies. More than half of the PG patients have underlying diseases; the most common being inflammatory bowel disease (IBD). The progression of PG in IBD patients is seen after the onset of IBD, usually during its exacerbation. On the other hand, PG may follow a course independent of the intestinal disease. We present a case of an 18-year-old young male with PG that presented before being diagnosed with ulcerative colitis as an associated condition. He had a painful ulcerative lesion on his right shin with no previous gastrointestinal symptoms. This case suggests that investigating for underlying disorders is essential in PG patients despite the lack of symptoms other than the skin lesions.

Contrast-Enhanced Ultrasonography for the Evaluation of Crohn's Disease in Pediatric Patients.

BACKGROUND: Contrast-enhanced ultrasonography (CEUS) of the bowel wall has been suggested as an alternative imaging modality for the follow-up of children with Crohn's disease. To demonstrate the feasibility and clinical usefulness of CEUS in the estimation of Crohn's disease activity in children with endoscopy as the reference standard. METHOD: In this prospective study, 30 pediatric patients with Crohn's disease (24 males and 6 females; median age 14 years) underwent CEUS from December 2020 to August 2021. The simple endoscopic score for Crohn's disease, pediatric Crohn's disease activity index, serologic inflammatory markers, fecal calprotectin and CEUS perfusion parameters were assessed and compared between the inactive and active group based on endoscopic findings. RESULTS: CEUS was performed successfully in all 30 patients. Two patients showed mild adverse side effects such as temporary dysosmia. The active Crohn's disease group showed higher erythrocyte sedimentation rate (mm/hr) (13.0 vs. 2.0, P = 0.003), C-reactive protein (mg/dL) (4.7 vs. 0.55, P = 0.018) and fecal calprotectin (mcg/g) (1,503 vs. 237.5, P = 0.005). Among the quantitative parameters for CEUS, the mean gradient to the peak value was higher in the active group (1.18 vs. 0.93, P = 0.034). The sensitivity and specificity of the mean gradient to the peak value for predicting active Crohn's disease was 55.6% and 83.3%, respectively, with a cut-off of 1.09 (P = 0.015). CONCLUSION: CEUS can be a safe and specific diagnostic modality for Crohn's disease activity in children. Among quantitative CEUS parameters, the mean gradient to the peak value could be used to differentiate active and inactive Crohn's disease.

Effectiveness of High-Volume Therapeutic Plasma Exchange for Acute and Acute-on-Chronic Liver Failure in Korean Pediatric Patients.

Purpose: Liver transplantation (LT) is the only curative treatment for acute liver failure (ALF) and acute-on-chronic liver failure (ACLF). In high-volume therapeutic plasma exchange (HV-TPE), extracorporeal liver support filters accumulate toxins and improve the coagulation factor by replacing them. In this study, we aimed to evaluate the effectiveness of HV-TPE in pediatric patients with ALF and ACLF. Methods: We reviewed the records of children waiting for LT at Severance Hospital who underwent HV-TPE between 2017 and 2021. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), total and direct bilirubin (TB and DB), gamma-glutamyl transferase (GGT), ammonia, and coagulation parameter-international normalized ratio (INR) were all measured before and after HV-TPE to analyze the liver function. The statistical analysis was performed using IBM SPSS Statistics for Windows, version 26.0 (IBM Co., Armonk, NY, USA). Results: Nine patients underwent HV-TPE with standard medical therapy while waiting for LT. One had neonatal hemochromatosis, four had biliary atresia, and the other four had ALF of unknown etiology. Significant decreases in AST, ALT, TB, DB, GGT, and INR were noted after performing HV-TPE (930.38-331.75 IU/L, 282.62-63.00 IU/L, 11.75-5.59 mg/dL, 8.10-3.66 mg/dL, 205.62-51.75 IU/L, and 3.57-1.50, respectively, p<0.05). All patients underwent LT, and two expired due to acute complications. Conclusion: HV-TPE could remove accumulated toxins and improve coagulation. Therefore, we conclude that HV-TPE can be regarded as a representative bridging therapy before LT.

Significance of Follow-Up Ultrasonography 24 Hours Post-Reduction in Detecting Intussusception Recurrence.

PURPOSE: The objective of this study was to identify the significance of 24-hour post-reduction ultrasonography (US) in pediatric patients with intussusception. METHODS: A total of 229 patients with intussusception who were treated with saline reduction at Severance Children's Hospital between January 2014 and September 2020 were retrospectively reviewed. The 229 patients with successful saline reduction were divided into two groups: a recurrence at 24 hours group (R, n=41) and a non-recurrence group (NR, n=188). The full patient sample was divided into two groups: follow-up US (FU) or no follow-up US (NFU); the recurrence group was divided into follow-up (R-FU) and non-follow-up (R-NFU) subgroups, and stratified analyses were performed. RESULTS: There were no significant differences in age, sex, laboratory findings, symptoms, and sonographic findings between the NR and R groups. In the R group, 24 patients underwent follow-up US, and 17 patients did not. Specific sonographic findings were statistically significant in the R-FU group compared to the R-NFU group (p=0.002). The R-FU group had fewer admissions (p=0.012) and longer mean hospitalization times (p<0.001) than the R-NFU group. The NFU group had a 12.2% recurrence rate, while the R-FU group recurrence rate was 25.8% (p=0.0099), suggesting that the omission of some recurrent events and follow-up US was a significant variable in the recurrence of intussusception. The median time to recurrence was 21 hours which supports the 24-hour follow-up protocol. CONCLUSION: Twenty-four-hour follow-up US was shown to be valuable for detecting early recurrence of intussusception.

Tripodal RNA with 3' Overhangs Prevents RIG-I-Mediated Innate Immune Response.

RNA interference (RNAi) offers great promise in life science research and therapeutic development, as it easily achieves a potent target gene knockdown with high specificity. Since the conventional small interfering RNA (siRNA) structure, known as 19 bp double-stranded RNA (dsRNA) with 2-nucleotide (nt) 3' overhang, has been introduced to successfully elicit the RNAi in mammalian cells, a variety of structural variants of RNAi trigger have been developed. Our group previously reported branched, tripodal interfering RNA (tiRNA) structures as a multigene targeting RNA structure inducing RNAi. However, the immune stimulatory effect of branched tiRNA structure has not been thoroughly evaluated. In this study, we show that tiRNA with blunt ends triggers innate immune response in T98G cell and mouse macrophage cells, which is dependent upon the retinoic acid-inducible gene I (RIG-I), a well-known cytoplasmic dsRNA sensor. Interestingly, immune response triggered by tiRNA can be suppressed by the introduction of 2-nt 3' overhang structure. Our finding expands the structural diversity of RIG-I ligands and provides a guide to develop a safe multitargeting RNA structure for therapeutic application.